Nests of the Black-crowned Night Heron and the Snowy Egret were examined in five central Utah colonies in 1973 to determine the spatial distribution within the colony. Nest locations of the 1085 nests of the two species were plotted to the nearest foot with an alidade and plane table. Tests of randomness, clump size, association, segregation, and T distribution were utilized. No differences between species were noted for the distance to the nearest and the next nearest nest. The Night Heron nested closer to other Night Herons and more often than did the Snowy Egret which non-significantly selected either species to nest closest. The Snowy Egret nests were 1.7 times higher than the Night Heron nests. Both species nests were aggregated within the colony. The association between the species within the habitat was positive but were segregated within the colony. Nest succession within a colony indicates that the Snowy Egret becomes more selective as time progresses but that the Night Heron remains selective throughout the entire season.

This study was designed to determine if, by providing artificial nest sites, a raptorial predator could be attracted into an area where suitable sites are limited. The American Kestrel (Falco sparverius) was a common species in the area and nest boxes designed for their use were placed in three vegetational types in western Utah and eastern Nevada. Seventy boxes were available in 1975 and 110 in 1976. Kestrels nested both years in the salt-desert shrub community but were absent from the pinyon-juniper and riparian areas. Four other bird species nested in the latter two areas, however. In 1975 the nesting success was affected by severe weather including unseasonable cold and snow. In 1976 interaction with and predation by rodents affected utilization and success. Other factors such as existing hole-nesting populations, size, construction, and placement of the box also affect the rate of occupancy and number of boxes used.